_Writing ActiveX ISAPI Extensions_
by Al Williams


Example 1:
Public Sub VBISAPI(server as Object)
 . . .
End Sub

Example 2:
<A HREF=http://www.al-
williams.com/awc/scripts
/cbisapi.dll?hilo.dll:Guess+newgame> 
Click to begin 
</A>

Example 3:
(a)
Dim x as Variant
server.ServerVariable "HOST_NAME",x
server.Write x
server.ServerVariable "SCRIPT_NAME",x
server.Write x

(b)
Dim x as Variant
Dim y as Variant
server.ServerVariable "HOST_NAME",x
server.ServerVariable "SCRIPT_NAME",y
server.Write x & y

Example 4:
Dim s as String
s=server.ParsedQueryString("HI")

Example 5:
(a)
<% EntryTime = now
       Validated = False
%>

(b)
Logged on since <%= EntryTime %>

(c)
<% if Validated then %>
<B>Data Entry Successful!</B>
<% end if %>




Listing One
VERSION 1.0 CLASS
BEGIN
  MultiUse = -1  'True
END
Attribute VB_Name = "DLL"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = True
Attribute VB_PredeclaredId = False
Attribute VB_Exposed = True
Option Explicit
Private Sub svrerr(server As Object, errstr As String)
server.WriteLine "Error: " & errstr
server.statcode = 400
server.retval = 4
End Sub

Private Sub Win(server As Object)
server.WriteLine "<HTML><HEAD><TITLE>I Win</TITLE></HEAD><BODY>"
server.WriteLine "I got it right!</BODY></HTML>"
End Sub

Private Sub GuessAgain(server As Object, Hi As Long, Lo As Long)
Dim servername As Variant
Dim script As Variant
server.WriteLine "<HTML><HEAD><TITLE>HiLo!</TITLE></HEAD><BODY>"
server.WriteLine "My guess is " & CInt((Hi + Lo) / 2) & "<P>"
server.ServerVariable "SERVER_NAME", servername
server.ServerVariable "SCRIPT_NAME", script
server.WriteLine "Is my guess:<P>"
server.Write "<FORM ACTION=http://" & servername
server.Write "/" & script
server.WriteLine "?HILO.DLL:Guess+HI=" & Hi & "+LO=" & Lo & " METHOD=POST>"
server.WriteLine "High <INPUT TYPE=RADIO NAME=ANSWER VALUE=HI><P>"
server.WriteLine "Correct <INPUT TYPE=RADIO NAME=ANSWER VALUE=OK><P>"
server.WriteLine "Low <INPUT TYPE=RADIO NAME=ANSWER VALUE=LO><P>"
server.WriteLine "<INPUT TYPE=SUBMIT>"
server.WriteLine "</FORM>"
server.WriteLine "</BODY></HTML>"
End Sub

Public Sub Guess(server As Object)
 Dim Guess As Long
 Dim Hi As Long
 Dim Lo As Long
 Dim pos As Long
 Dim ans As String
 pos = InStr(1, server.QueryString, "HI=", vbTextCompare)
 If pos = 0 Then
   svrerr server, "Can't find HI"
   Exit Sub
 End If
 Hi = Val(Mid(server.QueryString, pos + 3))
 pos = InStr(1, server.QueryString, "LO=", vbTextCompare)
 If pos = 0 Then
   svrerr server, "Can't find LO"
   Exit Sub
 End If
 Lo = Val(Mid(server.QueryString, pos + 3))
 If server.ContentLength = 0 Then
  GuessAgain server, Hi, Lo
 Else
  Guess = (Hi + Lo) / 2
  pos = InStr(1, server.Content, "ANSWER=", vbTextCompare)
  If pos = 0 Then
    svrerr server, "Form error"
    Exit Sub
  End If
 ans = Mid(server.Content, pos + 7, 2)
 If ans = "OK" Then Win server
 If ans = "LO" Then GuessAgain server, Hi, Guess
 If ans = "HI" Then GuessAgain server, Guess, Lo
 If ans <> "OK" And ans <> "LO" And ans <> "HI" Then svrerr server, "Unknown Response: " & server.Content
End If
End Sub

Listing Two
<HTML>
<HEAD>
<TITLE>Play Hi-Lo!</TITLE>
</HEAD>
<BODY>
I'll guess your number.<BR>
Think of a number between 1 and 1024 and I'll guess it.<BR>
Think of your number and
<A HREF=http://www/scripts/cbisapi.dll?HILO.DLL:GUESS+HI=1024+LO=1>
click here to play</A>
</BODY>
</HTML>

